Patterns of Electrocardiographic Abnormalities in Children with Hypertrophic Cardiomyopathy.

Hypertrophic cardiomyopathy (HCM), a common cardiomyopathy in children, is an important cause of morbidity and mortality. Early recognition and appropriate management are important. An electrocardiogram (ECG) is often used as a screening tool in children to detect heart disease. The ECG patterns in children with HCM are not well described.ECGs collected from an international cohort of children, and adolescents (≤ 21 years) with HCM were reviewed. 482 ECGs met inclusion criteria. Age ranged from 1 day to 21 years, median 13 years. Of the 482 ECGs, 57 (12%) were normal. The most common abnormalities noted were left ventricular hypertrophy (LVH) in 108/482 (22%) and biventricular hypertrophy (BVH) in 116/482 (24%) Of the patients with LVH/BVH (n = 224), 135 (60%) also had a strain pattern (LVH in 83, BVH in 52). Isolated strain pattern (in the absence of criteria for hypertrophy) was seen in 43/482 (9%). Isolated pathologic Q waves were seen in 71/482 (15%). Pediatric HCM, 88% have an abnormal ECG. The most common ECG abnormalities were LVH or BVH with or without strain. Strain pattern without hypertrophy and a pathologic Q wave were present in a significant proportion (24%) of patients. Thus, a significant number of children with HCM have ECG abnormalities that are not typical for "hypertrophy". The presence of the ECG abnormalities described above in a child should prompt further examination with an echocardiogram to rule out HCM.

Impact of Obesity on Left Ventricular Thickness in Children with Hypertrophic Cardiomyopathy.

Obesity is associated with additional left ventricular hypertrophy (LVH) in adults with hypertrophic cardiomyopathy (HCM). It is not known whether obesity can lead to further LVH in children with HCM. Echocardiographic LV dimensions were determined in 504 children with HCM. Measurements of interventricular septal thickness (IVST) and posterior wall thickness (PWT), and patients' weight and height were recorded. Obesity was defined as a body mass index (BMI) ≥ 99th percentile for age and sex. IVST data was available for 498 and PWT data for 484 patients. Patient age ranged from 2 to 20 years (mean ± SD, 12.5 ± 3.9) and 340 (68%) were males. Overall, patient BMI ranged from 7 to 50 (22.7 ± 6.1). Obesity (BMI 18-50, mean 29.1) was present in 140 children aged 2-19.6 (11.3 ± 4.1). The overall mean IVST was 20.5 ± 9.6 mm and the overall mean PWT was 11.0 ± 8.4 mm. The mean IVST in the obese patients was 21.6 ± 10.0 mm and mean PWT was 13.3 ± 14.7 mm. The mean IVST in the non-obese patients was 20.1 ± 9.5 mm and mean PWT was 10.4 ± 4.3 mm. Obesity was not significantly associated with IVST (p = 0.12), but was associated with increased PWT (0.0011). Obesity is associated with increased PWT but not IVST in children with HCM. Whether obesity and its impact on LVH influences clinical outcomes in children with HCM needs to be studied.

Risk factors for lethal arrhythmic events in children and adolescents with hypertrophic cardiomyopathy and an implantable defibrillator: An international multicenter study.

BACKGROUND: Predictors of risk of lethal arrhythmic events (LAE) is poorly understood and may differ from adults in children with hypertrophic cardiomyopathy (HCM). OBJECTIVE: The purpose of this study was to determine predictors of LAE in children with HCM. METHODS: A retrospective data collection was performed on 446 children and teenagers 20 years and younger (290 [65%] male; mean age 10.1 ± 5.7 years) with idiopathic HCM from 35 centers. Patients were classified as group 1 (HCM with LAE) if having a secondary prevention implantable cardioverter-defibrillator (ICD) or primary prevention ICD with appropriate interventions or group 2 (HCM without LAE) if having a primary prevention ICD without appropriate interventions. RESULTS: There were 152 children (34%) in group 1 and 294 (66%) in group 2. Risk factors for group 1 by univariate analysis were septal thickness, posterior left ventricular (LV) wall thickness, lower LV outflow gradient, and Q wave > 3 mm in inferior electrocardiographic leads. Factors not associated with LAE were family history of SCD, abnormal blood pressure response to exercise, and ventricular tachycardia on ambulatory electrocardiographic monitoring. Risk factors for SCD by multivariate analysis were age at ICD placement (hazard ratio [HR] 0.9; P = .0025), LV posterior wall thickness z score (HR 1.02; P < .005), and LV outflow gradient < 30 mm Hg (HR 2.0; P < .006). LV posterior wall thickness z score ≥ 5 was associated with LAE. CONCLUSION: Risk factors for LAE appear different in children compared to adults. Conventional adult risk factors were not significant in children. Further prospective studies are needed to improve risk stratification for LAE in children with HCM.

Hemodynamic effects of sustained postoperative cardiac resynchronization therapy in infants after repair of congenital heart disease: Results of a randomized clinical trial.

BACKGROUND: It is unknown whether continuous cardiac resynchronization therapy (CRT) can lead to sustained improvement in hemodynamics after surgery for congenital heart disease (CHD). OBJECTIVE: We investigated whether CRT improves cardiac index (CI) and blood pressure in infants after biventricular repair of CHD. METHODS: We randomized infants younger than 4 months after biventricular CHD surgery to standard care or standard care plus CRT for 48 hours or until extubation if sooner. Change in the primary outcome of CI and blood pressure over time was compared between groups. For subgroup analysis, QRS duration was considered prolonged if greater than the 98th percentile. RESULTS: Forty-two patients were randomized: 21 controls and 21 patients receiving CRT (median weight 4 kg). There were no identified adverse events from pacing. The change in CI over time was not different between patients receiving CRT and controls, but trended toward improvement in patients with wide QRS who received CRT (n = 9) vs controls with wide QRS (n = 8) (+1.65 (0.86) L/(min·m2); P = .06). Controls with wide QRS experienced the smallest increase in CI (0.33 L/(min·m2)). Blood pressure was significantly higher in infants with wide QRS who received CRT than in controls (+7.14 (3.08) mm Hg; P = .02). Serum lactate level, catecholamine use, ventilation time, and length of intensive care unit stay were similar between the 2 groups. CONCLUSION: CRT improved blood pressure and a trend toward higher CI in infants after repair of biventricular CHD with prolonged QRS duration. These findings warrant further study of CRT to improve postoperative recovery in infants with electrical dyssynchrony.

Early Diagnosis and Repair of Double Saccular Aneurysms of the Aortic Arch Associated With Aortic Coarctation in an Infant With Loeys-Dietz Syndrome.

Multiple saccular aneurysms of the thoracic aorta in neonates and infants are exceedingly rare. An association of these aneurysms with Loeys-Dietz syndrome (LDS) in older age-groups is well known. This case report describes the diagnosis and subsequent successful repair of aortic coarctation associated with double saccular aneurysms of the thoracic aorta in patient with LDS during the first year of life.

Undiagnosed heart disease leading to sudden unexpected death in childhood: a retrospective study.

OBJECTIVES: Heart disease accounts for a significant proportion of sudden unexpected deaths among children. We describe here demographic features, pathological conditions, and the frequency of premonitory symptoms in a retrospective series of cases of sudden unexpected cardiac death (SUCD) attributable to undiagnosed structural heart disease. METHODS: A chart review of autopsies involving children 0 to 17 years of age that were performed at the Hospital for Sick Children (Toronto, Ontario, Canada) between 1984 and 2003 was conducted. Cases of sudden unexpected death within 24 hours after clinical presentation with previously undetected fatal heart disease were included. Cases with multiple or thoracic trauma and chronic or multisystem disease were excluded. RESULTS: During the 20-year study period, 4926 autopsies were performed. A total of 103 cases (2.1%), involving 51 male patients and 52 female patients 1 day to 15 years of age (mean: 2.9 ± 4.2 years), were diagnosed as having SUCD. The most common diagnoses were myocarditis (n = 37 [35.9%]), hypoplastic left heart syndrome (HLHS) (n = 19 [18.4%]), dilated cardiomyopathy (DCM) (n = 16 [16.5%]), coronary artery anomalies (n = 6 [5.8%]), and aortic stenosis (n = 5 [4.9%]). There was a significant difference in the mean age of presentation between leading causes of SUCD (6.5 days for HLHS, 1.7 years for DCM, and 5.4 years for myocarditis; P < .0001). Of 103 cases, 27 (26.2%) had premonitory symptoms documented. CONCLUSION: SUCD accounted for 2.1% of all autopsies, and HLHS, DCM, and myocarditis were the 3 most common diagnoses, which presented at increasing ages.

Resolution of dyssynchronous left ventricular failure via cardiac resynchronization and subsequent radiofrequency ablation in an infant with pre-excitation.

Ventricular pre-excitation causing reversible left ventricular (LV) systolic dysfunction has been reported in adults and children. We describe severe heart failure secondary to ventricular pre-excitation in a 3-month-old girl who presented with echocardiographic evidence of marked intraventricular dyssynchrony. The patient was initially considered for transplantation, but dual chamber left atrioventricular epicardial pacing initiated at 4.5 months of age resulted in a marked clinical and echocardiographic improvement. Five years later, successful radiofrequency ablation resulted in loss of pre-excitation and reversal of LV dyssynchrony, thus allowing pacemaker explantation. To our knowledge, this is one of very few reported cases of pre-excitation-induced cardiomyopathy affecting a young infant and the only case palliated with resynchronization pacing.

Neonatal rhabdomyoma causing right ventricular inflow obstruction with duct-dependent pulmonary blood flow: successful stenting of PDA.

We describe an infant with the antenatal diagnosis of a large intracardiac rhabdomyoma causing tricuspid inflow obstruction. Postnatal cyanosis and arterial hypoxemia prompted commencement of intravenous prostaglandin E1 with immediate improvement in saturations. Clinical and genetic testing confirmed diagnosis of tuberous sclerosis. To secure ductal patency, two tandem coronary stents were implanted via an antegrade approach. Several episodes of long RP atrio-ventricular re-entrant tachycardia were observed. At 7(1/2) months of age, the tumor was no longer obstructive to tricuspid inflow, ductal flow was highly restrictive and there was no recurrence of supraventricular tachycardia.